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Controlled-Rate Freezer
Installation | 9
LN
2
Connections
The unit requires a user-supplied, clean, low pressure
regulated (22 PSIG + 30%) liquid nitrogen supply. Pressure
higher than recommendations may degrade unit performance
as these could hold the fill solenoids partially open. A 60 PSIG
liquid nitrogen pressure relief valve is located on the back of
the unit (
).
Connect the transfer hose between the low pressure, liquid
outlet of the nitrogen supply tank (not the gas outlet) and the
LN
2
supply inlet located on the back of the unit
. The
unit is shipped with a removable plastic protective cap over
the LN
2
supply inlet to keep debris out of the solenoids and
protect the inlet threads during shipping and handling. Do not
over-tighten the fitting as it may damage the internal
plumbing. Arrangements should be made to collect the water
which will form on the transfer hose from melted frost, to
prevent a potential slip or fall hazard.
After the transfer hose has been connected, open the supply
valve and check the connections for leaks.
Electrical Connections
See the serial tag on the side of the unit for electrical
specifications.
1. Verify the ON/OFF switch on the right side of the unit is
OFF.
2. Connect the appropriate line cord to the power inlet on
the rear of the unit.
3. Connect the unit to a grounded, dedicated circuit.
Sample Thermocouple
Connection
1. Open the unit door.
2. Locate the thermocouple connector in the front upper
right corner of the chamber.
3. Install the supplied sample thermocouple in the correct
orientation.
4. Close the unit door.
Note:
The freezer has been calibrated at the factory with the
1.2/2.0 ml sample thermocouple probe installed in the internal
thermocouple connector. Refer
section to
calibrate an external thermocouple probe.
Figure 4. Sample Thermocouple Connection
CAUTION:
The flair connections on the ends of
the transfer hose do not require any sealant. Pipe
dope or Teflon
®
tape may cause contamination
of the liquid fill solenoids or leaks at the hose
connections because these cannot withstand the
extreme low temperatures of this application.
CAUTION:
Do not disable or remove the
pressure relief valve.
CAUTION:
The ON/OFF switch is the main
disconnect device for the unit.Position the unit so
the switch is easily accessible.